In separation processes (e.g., extraction, leaching, drying, freeze, drying, etc.) where mass and/or a combination of mass and heat transfer are involved, the physical form of feed, i.e., the particle size and the attendant ratio of surface area to volume and volume to mass (specific volume) usually has a great impact on the efficiency of the process. This efficiency can be expressed in terms of using less solvent or energy, faster processing rate, higher percent recovery, and in many cases, higher quality of the final products. For example, in leaching by organic solvents or supercritical fluids (SCF), the greater the area of the solute exposed to solvent, the more efficient the process is. Likewise, in freeze drying, the heat flux and the rate of sublimation is directly proportional to the subject area of the material under process.
When extracting desired substances from plant and animal materials, such as tissues, cells, and the like, it is important that the particle size of the material being extracted be as small as possible. There are three reasons why small size is important: (1) the action or processes involved in obtaining small particle size break the walls, membranes and structures which physically protect and surround cells, organelles, and extracellular materials; (2) it is necessary in extraction processes to expose as much of the molecular species to be extracted as is possible to the solvent; and (3) in thermal extraction, it is important that molecular species be physically exposed.
Disruption of membranes, and maximum exposure can be obtained by treating plant or animal materials at or below their brittleness temperature. This is defined herein as the temperature below which a frozen material fractures into small particles when stress is applied thereto.
In order to prepare animal or plant derived materials, i.e., tissues, organs, cells and organelles for separation processes such as extraction and leaching via aqueous solvents, organic solvents, SCF, and/or application of thermal energy, the solutes (usually contents of the cells, protoplasm and/or membranes) should become easily available and exposed to the extracting media. This means that the cell membrane should be ruptured. The greater the ratio of surface area to volume of such animal derived solutes, the more efficient the process is.
Due to inherent thermal sensitivity of animal derived material, in preparing of such materials, one should avoid using "heat" over biomolecular breakdown temperature, because it may cause undesirable reactions (e.g., protein denaturation, lipid and carbohydrate breakdown, inactivation of desirable biomolecules) and production of undesirable products (e.g., Maillard Reaction Products, pyrolysis products) which, in turn, may adversely affect the separation process. Consequently, preparation of animal derived materials for separation processes should be done at the minimum possible temperature.
On the other hand, some animal derived materials, due to their inherent rheological behaviors, cannot be homogenized at regular temperatures. For example, adipose tissues and omentum cannot be homogenized (ground) at room temperature, refrigerator temperature, or even higher freezing temperatures. The high plasticity of these tissues is not compatible with grinding processes. In traditional methods, phosphate buffered saline (PBS) or water is added as a "filter" to animal fatty tissues in order to make the homogenization possible. In other words without a medium, the tissue cannot be disintegrated by mere homogenization. Addition of aqueous phase, however, requires its subsequent removal from the system by a time consuming or energy consuming step such as centrifugation or freeze drying.
In conclusion, for preparation of animal and plant derived materials for separation processes, a method is needed which does not require an extra phase or substance, ruptures the cell membranes and walls effectively, increases the exposing surface area of the cell contents to the separating driving force (solvent, SCF, thermal energy, vacuum, etc.), does not involve damaging heat treatment, is compatible with biomolecules, technology adaptable and is economically feasible.
It is an object of this invention to rapidly prepare animal or plant materials for extraction by preparing said materials at temperatures at or below their brittleness temperature in order to enable fracture of said materials into particles with optimum size and attendant ratios of surface area to volume and volume to mass.
It is a further object of the invention to provide an improved method for obtaining desirable substances from animal and plant materials, including but not limited to lipids, carbohydrates, proteins and all other biomolecules which does not effect or has only minimal effect on the structure or reactivity of said biomolecules.
Yet another object of this invention is to extract materials from animal and plant which have been treated at brittleness temperatures or below to obtain desired substances therefrom.
Yet a further object of the invention is to provide a method of separation such as drying, freeze drying, leaching and extraction using aqueous and organic solvents and/or supercritical fluids (SCFs) in connection with materials fractured at or below their brittleness temperatures.
How these and other objects of the invention are accomplished will be seen from the disclosure which follows.